The present invention relates to an apparatus for selecting a power transmission system of a four-wheel drive motor vehicle having a sub-transmission for providing a high speed range four-wheel drive, and a low speed range four-wheel drive, and more particularly to an apparatus for manually changing a two-wheel drive power transmission to a high speed range four-wheel drive or a low speed range four-wheel drive.
U.S. Pat. No. 4,356,879 discloses a transmission provided with a transfer clutch for changing the two-wheel drive power transmission to the four-wheel drive power transmission, with a clutch for the sub-transmission, and with a selecting device for operating both clutches for selecting the two-wheel drive, high speed range four-wheel drive, or low speed range four-wheel drive. The selecting device comprises an actuating rail operated by a select lever, a fixed rail, and a shift rail for operating the clutch for the sub-transmission. Such a construction comprising three rails renders the device complicated and large in size. Farther, the actuating rail, the shift rail and a select lever for operating the actuating rail are at offset or staggered positions. Accordingly, the movement of the actuating rail causes moments in elements of the device to which produce frictional resistances and torsions, which detract from the operability of the device.